1. Field of the Invention
The present invention relates to a laminate used for wrapping materials and containers, and more particularly to a biodegradable laminate comprising a base material and a biodegradable copolymer, the biodegradable copolymer being laminated on the base material. In addition, the present invention relates to a wrapping material comprising the laminate and a container made of the laminate.
2. Discussion of the Related Art
Conventionally, in the field of wrapping, laminates comprising plastic materials have been widely used as wrapping materials. In addition, as for containers, particularly paper containers, laminates comprising paper and plastics, the plastics being pasted together with the paper, have been used to form paper boxes, paper cups, paper trays, and the like. Such laminates are used because natural materials, such as paper, alone would not give sufficient mechanical strength and waterproofness. Presently, in order to meet requirements in such properties as rigidity, impact resistance, leakage inhibiting ability, heat seal property, and the like, polyolefins, such as polyethylenes and polypropylenes, are widely used as plastic materials for the above-described laminates.
In general, the mainstream of the paper containers mentioned above is a disposable container after a single use, and the paper containers are littered to be subjected to incineration treatment or land fill. However, when the paper containers are scattered as wastes in natural environments, the polyolefins remain without being degraded, thereby causing environmental pollution with the polyolefins.
In recent years, plastics which are dumped in large quantities have been noted as a pollutive source in the natural environments. In order to solve this problem, biodegradable plastics have been marked as plastics which are "gentle to environment," the biodegradable plastic being subjected to reduction to CO.sub.2 and H.sub.2 O when allowing the plastics to stand in natural environments by actions of microorganisms living in the environments. Since the biodegradable plastics undergo degradation by actions of microorganisms living in soils, rivers, and seawater during a period of several weeks to several years, paper containers made of such plastics in the end undergo degradation to CO.sub.2 and H.sub.2 O, including even paper constituting the paper containers. Therefore, biodegradable plastics have been recently developed as a means of solving problems inherent in plastic wastes.
Presently, the following two kinds of aliphatic polyesters have been developed as the biodegradable plastics described above.